function make_sprite(x, y, anim, speed)
    s = {
        x=x, y=y, anim=animations[anim], speed=speed,
        frame=0, last_update=t(),
        flip_x=false, flip_y=false, loop=false,
    }
    return s
end

function update_sprite(s)
    local now = t()
    if s.last_update == 0 then
        s.last_update = now
        return
    end
    if s.speed != 0 then
        if now - s.last_update > s.speed then
            s.frame += 1
            s.last_update = now
            if s.frame > #s.anim.frames then
                if s.loop then 
                    s.frame = 0
                else
                    s.speed = 0
                    s.frame = #s.anim.frames
                end
            end
        end
    end
end

function draw_sprite(s)
    spr(s.anim.frames[s.frame], s.x, s.y, s.anim.w, s.anim.h, s.flip_x, s.flip_y)
end